The invention relates to the field of space-based solar cell panels. More particularly, the present invention relates to a continuous trickle charging power sphere for providing attitude insensitive trickle power to a spacecraft having an attitude-oriented solar panel.
Many on-orbit spacecraft use flat solar panels for collecting solar power to operate the spacecraft. The solar panels may be large in size relative to spacecraft payload. The solar panels are flat panels that are unfurled or unfolded for exposing the flat solar array surfaces to the sun so that incident solar illumination is orthogonal to the plane of the solar panel for maximum solar power collection. When the solar panels are oriented off normal, so that the plane of the solar panel is no longer orthogonal to incident solar rays, then less than maximum solar power is collected. Worst still, when the solar panels are incidentally aligned to the incident solar light, that is, when striking the edge of the solar panel, no solar power is collected. When no solar power is collected, on board batteries provide backup power until the solar panels are again oriented to collect sufficient solar power to power the spacecraft. Hence, solar panels are disadvantageously susceptible to loss of power collection when edge wise oriented when incidentally aligned to solar light rays.
A spacecraft may suffer from environmental or operational disturbances that cause the attitude control system to malfunction, or otherwise cause the flat solar panels to lose lock on solar power collection. Under proper attitude control, a solar panel can be positioned orthogonal to unidirectional sun illumination for maximum collection of solar power. Attitude control of a spacecraft requires backup power when there is no solar power collection, when the solar panels are incidentally aligned. The loss of lock of solar power collection will drain backup battery power supplies unless lock is quickly regained. With loss of lock and with drained battery power supplies, the spacecraft may become completely dysfunctional and be lost in space. Hence, there then exists a lock up condition, which though the solar panels are functioning correctly, incidentally aligned solar panels cannot be oriented towards the sun in the presence of completely drained backup power. As a result, a number of satellites have been lost to space because the orthogonal orientation of the solar panels to incident sun light was lost for various reasons and after backup batteries power was completely drained and the satellites became a total loss. The loss of spacecraft is a significant problem to further space exploration. Some examples of loss satellites due to loss of solar power collection are the Lewis satellite that was lost in 1997, the Terrier satellite that was lost in 1999, and the Alexis satellite that was lost in 1993. The recurring loss of space satellites due to improperly aligned main solar panel orientation represents significant economic loss.
To solve the problems of solar panel orientation malfunctioning and the required attitude control for orthogonally orienting the solar panels away from sun illumination, a power sphere was invented, as described in the U.S. Pat. No. 6,127,621 issued on Oct. 03, 2000. The power sphere comprises a plurality of small flat panels arranged to approximate a spherical shape. The small flat panels are unfurled from supporting struts to form the approximate shape of a sphere. As such, the power sphere has omnidirectional facing panels that collect sun radiation regardless of the attitude of the power sphere, and hence, there is a lack of required attitude control and there is an inherent prevention of solar panel orientation malfunctioning. The small flat panels are suitable for powering, at all times of solar radiation, small microsatellites and picosatellites requiring relative small amounts of power, but the small flat panels have relatively small surface areas and are unsuitable for powering large spacecraft having large power requirements. These and other disadvantages are solved or reduced using the invention.
An object of the invention is to provide omnidirectional solar power collection system.
Another object of the invention is to provide omnidirectional solar power collection as a backup power supply for a conventional flat panel solar array in a composite solar power collection system.
Yet another object of the invention is to provide omnidirectional solar power collection power sphere as a backup power collector for a conventional flat panel solar array in a composite solar power collection system.
The invention is directed to a omnidirectional power source that is preferably a power sphere for satellite solar power backup to the main large flat solar array. The omnidirectional power source is preferably a long-term trickle charger for charging backup batteries as a supplemental power source to conventional flat solar panel arrays. The omnidirectional power source is preferably an omnidirectional power sphere. The omnidirectional power sphere is a light weight spherical solar power collector made of light weight thin film solar cells that are deployable into suitably large spheres, that do not require controlled orientation to generate backup solar power. The power sphere is installed in conjunction with conventional solar arrays on satellites as a composite solar power collection system, and deployed on-orbit to protect against solar panels lock when losing orientation toward the sun.
The invention ensures that there will be some trickle solar power available to enable communications, and therefore enable corrective action that may save the spacecraft when losing power collection from the main solar panel array. The trickle solar power sphere can be used to prevent complete draining of backup batteries. The system includes a deployable power sphere coupled to, or operating with, the main flat solar panel array. The main solar array panel and the power sphere are deployable solar collectors. Release and controlled sequences are used to deploy the power sphere and the main flat solar panel arrays. When deployed, the power sphere collects power at all times illuminated particularly when the main flat panel solar arrays lose lock on solar illuminations when edgewise aligned to solar rays when the main solar arrays do not collect power so that at all times of solar illumination, at least some trickle power from the power sphere is received, well suited for generating recovery and backup power that can be further used as trickle charging power for charging backup batteries. The power generated by the power sphere is used to trickle charge batteries of the main power systems or auxiliary batteries of an emergency system. These and other advantages will become more apparent from the following detailed description of the preferred embodiment.